I have a 90 gallon fish/coral tank that I just added a 48" Current light system with the 150 W Metal Halides. I have never used Halides, and am seeing an almost instantaneous effect especially on my Duncan Coral. However I notice my water temperature has increased a few degrees. So I turned down my heater, and turned off the Halides until the temperature comes down, however I know I need to fix the issue. Can I get advice from the experts out there how to remedy this. Also I am really looking forward to adding more variety of corals, and also would like some suggestions.

Well the heat from halides has always been a problem thats why people are switching to led's no heat. You can try adding a couple of computer fans in the hood or raise the hood a little higher off the water surface.

That would work but there very expensive to buy probable around $500 to $600 for that size tank plus the cost to run it. It would be cheaper for you to buy new led light then to buy the chiller. Two taotronic dimmable unit would be around $300 I just bought two for my 90 very bright.